1. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Ewha Womans University Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Ewha Womans University Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Korea.
3. Informatization Department, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, Seoul, Korea.